The function of Ensembl gene identifier ENSG00000151929 (BAG3, BAG cochaperone 3) is as follows. Co-chaperone and adapter protein that connects different classes of molecular chaperones including heat shock proteins 70 (HSP70s), e.g. HSPA1A/HSP70 or HSPA8/HSC70, and small heat shock proteins (sHSPs), e.g. HSPB8 (PubMed:27884606, PubMed:30559338). Acts as a nucleotide-exchange factor (NEF) promoting the release of ADP from HSP70s, thereby triggering client protein release (PubMed:27884606, PubMed:30559338). Nucleotide release is mediated via BAG3 binding to the nucleotide-binding domain (NBD) of HSP70s, whereas client release is mediated via binding to the substrate-binding domain (SBD) (PubMed:27474739, PubMed:9873016). Has anti-apoptotic activity (PubMed:10597216). Plays a role in the HSF1 nucleocytoplasmic transport (PubMed:26159920). {ECO:0000269|PubMed:10597216, ECO:0000269|PubMed:24318877, ECO:0000269|PubMed:26159920, ECO:0000269|PubMed:27474739, ECO:0000269|PubMed:27884606, ECO:0000269|PubMed:30559338, ECO:0000269|PubMed:9873016}.